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Auto merge of #3781 - uniphil:write_with_newline_false_positive, r=oli-obk

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Don't check [print/write]_with_newline on raw strings

Some tests for #3778 and some maybe-not-the-greatest code that passes those tests!

I didn't run `fmt` because a) it doesn't seem to install on nightly for me, and b) on stable it wanted to apply formatting to over 90 files. Happy to make any tweaks though!

I suspect this contribution may require more than just tweaks. I'm still sort of new to rust so it may not be idiomatic, and the specific approach I took feels a little heavy-handed and brittle. I'm happy to make changes with some guidance, or equally happy if this gives a starting place for someone else to do it better :)
This commit is contained in:
bors 2019-02-20 16:37:32 +00:00
commit 027dde92e2
5 changed files with 120 additions and 20 deletions
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55
clippy_lints/src/write.rs
View file

@ -5,7 +5,7 @@ use rustc_errors::Applicability;
use std::borrow::Cow;
use syntax::ast::*;
use syntax::parse::{parser, token};
use syntax::tokenstream::TokenStream;
use syntax::tokenstream::{TokenStream, TokenTree};
/// **What it does:** This lint warns when you use `println!("")` to
/// print a newline.
@ -200,8 +200,8 @@ impl EarlyLintPass for Pass {
}
} else if mac.node.path == "print" {
span_lint(cx, PRINT_STDOUT, mac.span, "use of `print!`");
if let Some(fmtstr) = check_tts(cx, &mac.node.tts, false).0 {
if check_newlines(&fmtstr) {
if let (Some(fmtstr), _, is_raw) = check_tts(cx, &mac.node.tts, false) {
if check_newlines(&fmtstr, is_raw) {
span_lint(
cx,
PRINT_WITH_NEWLINE,
@ -212,8 +212,8 @@ impl EarlyLintPass for Pass {
}
}
} else if mac.node.path == "write" {
if let Some(fmtstr) = check_tts(cx, &mac.node.tts, true).0 {
if check_newlines(&fmtstr) {
if let (Some(fmtstr), _, is_raw) = check_tts(cx, &mac.node.tts, true) {
if check_newlines(&fmtstr, is_raw) {
span_lint(
cx,
WRITE_WITH_NEWLINE,
@ -252,8 +252,9 @@ impl EarlyLintPass for Pass {
}
/// Checks the arguments of `print[ln]!` and `write[ln]!` calls. It will return a tuple of two
/// options. The first part of the tuple is `format_str` of the macros. The second part of the tuple
/// is in the `write[ln]!` case the expression the `format_str` should be written to.
/// options and a bool. The first part of the tuple is `format_str` of the macros. The second part
/// of the tuple is in the `write[ln]!` case the expression the `format_str` should be written to.
/// The final part is a boolean flag indicating if the string is a raw string.
///
/// Example:
///
@ -263,34 +264,49 @@ impl EarlyLintPass for Pass {
/// ```
/// will return
/// ```rust,ignore
/// (Some("string to write: {}"), Some(buf))
/// (Some("string to write: {}"), Some(buf), false)
/// ```
fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (Option<String>, Option<Expr>) {
fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (Option<String>, Option<Expr>, bool) {
use fmt_macros::*;
let tts = tts.clone();
let mut is_raw = false;
if let TokenStream(Some(tokens)) = &tts {
for token in tokens.iter() {
if let (TokenTree::Token(_, token::Token::Literal(lit, _)), _) = token {
match lit {
token::Lit::Str_(_) => break,
token::Lit::StrRaw(_, _) => {
is_raw = true;
break;
},
_ => {},
}
}
}
}
let mut parser = parser::Parser::new(&cx.sess.parse_sess, tts, None, false, false);
let mut expr: Option<Expr> = None;
if is_write {
expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
Ok(p) => Some(p.into_inner()),
Err(_) => return (None, None),
Err(_) => return (None, None, is_raw),
};
// might be `writeln!(foo)`
if parser.expect(&token::Comma).map_err(|mut err| err.cancel()).is_err() {
return (None, expr);
return (None, expr, is_raw);
}
}
let fmtstr = match parser.parse_str().map_err(|mut err| err.cancel()) {
Ok(token) => token.0.to_string(),
Err(_) => return (None, expr),
Err(_) => return (None, expr, is_raw),
};
let tmp = fmtstr.clone();
let mut args = vec![];
let mut fmt_parser = Parser::new(&tmp, None, Vec::new(), false);
while let Some(piece) = fmt_parser.next() {
if !fmt_parser.errors.is_empty() {
return (None, expr);
return (None, expr, is_raw);
}
if let Piece::NextArgument(arg) = piece {
if arg.format.ty == "?" {
@ -312,11 +328,11 @@ fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (O
ty: "",
};
if !parser.eat(&token::Comma) {
return (Some(fmtstr), expr);
return (Some(fmtstr), expr, is_raw);
}
let token_expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
Ok(expr) => expr,
Err(_) => return (Some(fmtstr), None),
Err(_) => return (Some(fmtstr), None, is_raw),
};
match &token_expr.node {
ExprKind::Lit(_) => {
@ -366,7 +382,14 @@ fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (O
}
// Checks if `s` constains a single newline that terminates it
fn check_newlines(s: &str) -> bool {
// Literal and escaped newlines are both checked (only literal for raw strings)
fn check_newlines(s: &str, is_raw: bool) -> bool {
if s.ends_with('\n') {
return true;
} else if is_raw {
return false;
}
if s.len() < 2 {
return false;
}

18
tests/ui/print_with_newline.rs
View file

@ -21,4 +21,22 @@ fn main() {
print!("Hello {} {}\n\n", "world", "#2");
println!("\ndon't\nwarn\nfor\nmultiple\nnewlines\n"); // #3126
println!("\nbla\n\n"); // #3126
// Escaping
print!("\\n"); // #3514
print!("\\\n"); // should fail
print!("\\\\n");
// Raw strings
print!(r"\n"); // #3778
// Literal newlines should also fail
print!(
"
"
);
print!(
r"
"
);
}

26
tests/ui/print_with_newline.stderr
View file

@ -24,5 +24,29 @@ error: using `print!()` with a format string that ends in a single newline, cons
LL | print!("{}/n", 1265);
| ^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors
error: using `print!()` with a format string that ends in a single newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:27:5
|
LL | print!("//n"); // should fail
| ^^^^^^^^^^^^^^
error: using `print!()` with a format string that ends in a single newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:34:5
|
LL | / print!(
LL | | "
LL | | "
LL | | );
| |_____^
error: using `print!()` with a format string that ends in a single newline, consider using `println!()` instead
--> $DIR/print_with_newline.rs:38:5
|
LL | / print!(
LL | | r"
LL | | "
LL | | );
| |_____^
error: aborting due to 7 previous errors

17
tests/ui/write_with_newline.rs
View file

@ -29,6 +29,21 @@ fn main() {
// Escaping
write!(&mut v, "\\n"); // #3514
write!(&mut v, "\\\n");
write!(&mut v, "\\\n"); // should fail
write!(&mut v, "\\\\n");
// Raw strings
write!(&mut v, r"\n"); // #3778
// Literal newlines should also fail
write!(
&mut v,
"
"
);
write!(
&mut v,
r"
"
);
}

24
tests/ui/write_with_newline.stderr
View file

@ -27,8 +27,28 @@ LL | write!(&mut v, "{}/n", 1265);
error: using `write!()` with a format string that ends in a single newline, consider using `writeln!()` instead
--> $DIR/write_with_newline.rs:32:5
|
LL | write!(&mut v, "//n");
LL | write!(&mut v, "//n"); // should fail
| ^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 5 previous errors
error: using `write!()` with a format string that ends in a single newline, consider using `writeln!()` instead
--> $DIR/write_with_newline.rs:39:5
|
LL | / write!(
LL | | &mut v,
LL | | "
LL | | "
LL | | );
| |_____^
error: using `write!()` with a format string that ends in a single newline, consider using `writeln!()` instead
--> $DIR/write_with_newline.rs:44:5
|
LL | / write!(
LL | | &mut v,
LL | | r"
LL | | "
LL | | );
| |_____^
error: aborting due to 7 previous errors